Do you have the new probe kit from dc42?
If not then the height can vary with different light in the room, it's every sensitive in the original design.
Another RS Ormerod Mk1 meets the world
Retired now but I used to make....
CNC Machined Mk1 aluminium bed support plates for the Ormerod
CNC machined X-plates and ribs for Mk1 & Mk2 Ormerods
CNC machined bed support arms for the Mk2 Ormerod.
Dual Hot-End heatsink blocks.